The morphology and chemical composition of the urban PM10 near a steel plant in Apulia determined by scanning electron microscopy. Source Apportionment

PM10 samples were collected in a site of Apulia region (South-East Italy) near a steel plant when the winds were blowing from the NW and the SE to exclude and include, respectively, the contribution of the industrial source in order to study the aerosol particles in detail and attribute them to the most appropriate emission sources. Size, morphology and chemical composition of 6500 individual particles, with an equivalent spherical diameter (ESD) between 0.4 - 1 mu m, 1 - 2.5 mu m and 2.5 - 10 mu m, were analysed by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM EDX). These particles were classified in the thirteen groups: aluminosilicates, silicates, iron oxides, metal oxides, iron mixtures, aluminosilicates with sulphur, calcium sulphates, silicate-sulphate mixed particles, carbonates, carbonates-silicates, soot, biological particles and carbon rich particles. Source apportionment analyses were carried out separately for the three dimensional ranges considered and for the two wind directions from North-West and South-East and nine main sources were distinguished. The soil and the soot components are higher when the wind blow from the NW than the SE, while the anthropogenic sources are evident with the wind from the SE due to the presence of iron and carbonaceous particles characterized by typical spherical shapes and chemical elements as Ca, Na and K which could to be indicative of industrial activity. The single particle analysis let better identify the emission sources that persist on the territory, attributing to them the particles characterized by peculiar morphology and chemical composition.